no root file system question

["David Ashworth" <ahab@sonic.net>]

Hello, hope I am in the right area to ask this question.  If I am not,
please tell me a better place.  I am trying to install debian via the cd.  I
get to one area and I am stumped.  I get the message" no root file system is
defined.  please correct this from the partitioning menu." Now, I go to the
partitioning menu and go around and around in a loop and get the same no
root file system message.  I don't know what it wants. Maybe something
simple, but what?

I am using the second drive in my PC.  It is all Linux.  Here is what it
looks like: (hdb) 61.5 GB, #1 primary 59.3 GB B K lvm,    #5 logical 2.2 GB
F swap swap.

So, I am in this loop.  Where is this root file?  Is it on the CD?  I am new
to this, so I am a little confused.  Everything up to this step has gone OK.
Been reading the help files, but being as I am new to this, more confusion
than help.

Thank you for your help, Dave